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3 years ago

−3−4x≤21 pls help me

Mathematics

2 answers:

Sonja [21]3 years ago

5 0

Answer:

-7x<21

i think, I'm not fully sure what it's asking.

Step-by-step explanation:

kodGreya [7K]3 years ago

4 0

Answer:

x ≥ - 6

Step-by-step explanation:

Given

- 3 - 4x ≤ 21 ( add 3 to both sides )

- 4x ≤ 24

Divide both sides by - 4, reversing the symbol as a result of dividing by a negative quantity.

x ≥ - 6

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Directions: Classify if the given mathematical symbols illustrate equation or

marissa [1.9K]

Answer:

Inequalities if it has $\leq or \geq \\$ symbols

Equations if it has =

Step-by-step explanation:

5 0

3 years ago

Solve the system of equations

rewona [7]

Answer:

x = 1/4

y = -1/2

z = 9/4

Step-by-step explanation:

Here we have a system of 3 equations with 3 variables:

4*x + 2*y + 1 = 1

2*x - y = 1

x + 3*y + z = 1

The first step to solve this, is to isolate one of the variables in one of the equations, let's isolate "y" in the second equation:

2*x - y = 1

2*x - 1 = y

Now that we have an expression equivalent to "y", we can replace this in the other two equations:

4*x + 2*(2*x - 1) + 1 = 1

x + 3*(2*x - 1) + z = 1

Now let's simplify these two equations:

8*x - 1 = 1

7*x - 3 + z = 1

Now, in the first equation we have only the variable x, so we can solve that equation to find the value of x:

8*x - 1 = 1

8*x = 1 + 1 = 2

x = 2/8 = 1/4

Now that we know the value of x, we can replace this in the other equation to find the value of z.

7*(1/4) -3 + z = 1

7/4 - 3 + z = 1

z = 1 + 3 - 7/4

z = 4 - 7/4

z = 16/4 - 7/4 = 9/4

z = 9/4

Now we can use the equation y = 2*x - 1 and the value of x to find the value of y:

y = 2*(1/4) - 1

y = 2/4 - 1

y = 1/2 - 1

y = -1/2

Then the solution is:

x = 1/4

y = -1/2

z = 9/4

7 0

3 years ago

Evaluate the expression when c = -6 And y = 7 y - 9c

GrogVix [38]

The answer is 61. hope that help.

5 0

3 years ago

Read 2 more answers

Please help with this question!! I need serious help!!

asambeis [7]

Answer:

<h2>The circumference is multipled by 4.</h2>

Step-by-step explanation:

The formula of an area of a circle"

$A=\pi r^2$

The formula of a circumference of a circle:

$C=2\pi r$

The area multipled by 16:

$16A=16\pi r^2\\\\16A=\pi(4^2r^2)\\\\16A=\pi(4r)^2$

The radius has increased fourfold, therefore:

$C'=2\pi(4r)=4(2\pi r)=4C$

The circumference is multipled by 4.

You can calculate the area and check the circumference:

$r=11.6\ in\\\\A=\pi(11.6)^2=132.56\pi\\\\16A=(16)(134.56\pi)=2152.96\pi\ in^2$

Calculate the radius:

$\pi r^2=2152.96\pi$ divide both sides by π

$r^2=2152.96\to r=\sqrt{2152.96}\\\\r=46.4\ in$

Calculate the circumference of both circles:

$r=11.6\ in\\\\C=2\pi(11.6)=23.2\pi\ in$

$r=46.4\ in\\\\C'=2\pi(46.4)=92.8\pi\ in$

$\dfrac{C'}{C}=\dfrac{92.8\pi}{23.2\pi}=4\to C'=4C$

5 0

3 years ago

In ΔBCD, the measure of ∠D=90°, the measure of ∠C=77°, and CD = 41 feet. Find the length of BC to the nearest foot.

OLga [1]

Answer:

182 ft

Step-by-step explanation:

When you are not given a diagram, always draw one for yourself (see diagram).

When you have a right triangle (triangle with 90° angle), you can use the trigonometry ratios, You can remember them using SohCahToa. It is read like this:

sinθ = opposite/hypotenuse Soh

cosθ = adjacent/hypotenuse Cah

tanθ = opposite/adjacent Toa

"θ" means the angle of reference (the angle you are talking about).

We are looking for the length of BC, which is the hypotenuse. I labelled it "d" (lowercase D) because it is opposite to ∠D.

We know ∠C = 77°. This will be our angle of reference (replace θ).

The side we know is DC, also known as "b" (lowercase B) because it's opposite to ∠B. "b" is the adjacent side when θ = C because "b" is touching ∠C.

Take the general trig. formula that has hypotenuse and adjacent: (cosine ratio)

cosθ = adjacent/hypotenuse

Substitute the variables specific for this problem.

cosC = b/d

Substitute the values you know.

cos77° = (41 ft) / d

Isolate "d" to the left side

dcos77° = $d*\frac{41ft}{d}$ Multiply both sides by "d"

dcos77° = 41 ft

dcos77° / cos77° = 41 ft / cos77° Divide both sides by cos77°

d = 41 ft / cos77° Input into calculator

d = 182.261874....... ft Unrounded answer

d ≈ 182 ft Rounded to nearest foot (whole number)

Remember d = BC. It's often easier to use one letter for calculations.

Therefore the length of BC is about 182 feet.

8 0

3 years ago